MEMS Pressure Sensor ADC Clock Dithering for Ringing Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Microelectromechanical systems (MEMS) sensors face measurement errors due to underdamped responses caused by mechanical resonances, leading to ringing noise in pressure measurement systems, which affects accuracy.
Innovation Solution
The implementation of a sigma-delta analog to digital converter (ADC) with a dithered clock and a slope-controlled excitation signal, along with an array of MEMS pressure sensors with varying dimensions to reduce ringing noise through destructive interference, and the use of an oversampled ADC with a dithered clock to alleviate idle tones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a MEMS sensor is used for pressure measurement, then the sensor provides miniaturized electrical and mechanical components useful in various applications, but mechanical resonances cause underdamped responses leading to ringing noise that affects measurement accuracy
Solution Approach 1:
The patent applies dithering techniques that intentionally add controlled random variations to the excitation signal and sampling clock. This converts the harmful ringing noise caused by mechanical resonances into a broader spectrum noise that can be more effectively filtered, thereby improving measurement accuracy while maintaining the benefits of MEMS miniaturization
Solution Approach 2:
The patent modifies the excitation signal parameters by applying slope control to reduce high-frequency components that trigger mechanical resonances. Additionally, the sampling clock frequency is varied through dithering, which spreads the ringing noise across a broader frequency spectrum, allowing for more effective noise filtering and improved pressure measurement accuracy
2Measurement precision
If a sigma-delta ADC is used to convert the transducer signal, then the converter provides high-resolution digital output, but idle tones and narrow-band noise reduce measurement accuracy
Solution Approach 1:
The patent applies dithering to the sigma-delta ADC's sampling clock, which converts the harmful idle tones and narrow-band noise into a broader spectrum noise floor. This allows the high-resolution digital output capability of the sigma-delta ADC to be fully utilized while eliminating the accuracy-reducing idle tones through spectral spreading
Solution Approach 2:
The patent employs periodic dithering of the sampling clock frequency, which systematically varies the sampling rate to spread idle tones across a broader frequency range. This periodic modulation of the sampling clock, combined with the sigma-delta ADC's inherent oversampling capability, effectively eliminates narrow-band noise while preserving high-resolution conversion
Data Source
AI summary
According to an embodiment, a sensor circuit includes a sigma-delta analog to digital converter (ADC), a dithered clock coupled to the sigma-delta ADC, and a supply voltage circuit coupled to the sigma-delta ADC. The sigma-delta ADC is configured to be coupled to a low frequency transducer, and the dithered clock is configured to control of the sigma-delta ADC based on a dithered clock signal.